An anorectal abscess is a localized infection or pocket of pus near the anus and rectum. These can occur superficially or in the deeper tissues adjacent to the anus and rectum. Symptoms usually progress rapidly over a few days and typically consist of pain, pressure, swelling, fevers, and occasionally difficulties with urination. Some abscesses may drain spontaneously. Others may be drained in the office using local numbing medication or in the operating room under anesthesia. The method of drainage depends on the size and depth of the abscess.
Some patients have complete resolution of their symptoms after drainage of the abscess. Others will go on to develop an anal fistula, which is an abnormal tract or connection between the anal glands and the skin around the anus. The degree of symptoms from an anal fistula is highly variable. Some fistulae will intermittently become swollen and painful, whereas others may only produce a small amount of drainage. If is fistula is not bothersome to the patient, further treatment may not be necessary. If the fistula causes symptoms, then outpatient surgery is typically recommended. The specific surgical procedure for an anal fistula depends on the length and the depth of the fistula.